The present invention relates to a thermal transfer printing mechanism using an ink ribbon to form an image on image receiving sheet, and a facsimile device employing the mechanism. As shown in FIGS. 1 and 2, a conventional thermal transfer printing mechanism comprises, for example, a line type thermal head 11, a platen roller 13 for supporting the sheet 12 against the thermal head 11, and an ink ribbon 14 fed between the thermal head 11 and the sheet 12.
The thermal head 11 includes a heating array 15 comprising many heating elements arranged in the main scanning direction (i.e., the direction of sheet width). The heating elements heat the ink carried by the ink ribbon, so that the ink is melted and transferred to the sheet 12 according to the pattern of heated elements. The ink ribbon 14 tends to adhere to the sheet because of the melting or melted ink.
Usually, a guide member 16 is provided downstream of the thermal head 11 to separate the ink ribbon 14 from the sheet 12. The guide member 16 has a curve 16a around which the ink ribbon 14 is bent, to change the direction of the ink ribbon 14 as it is fed. The radius of curvature of the curve 16a is relatively large so that the ink ribbon 14 is fed smoothly.
However, as shown in FIG. 2, when one or more lateral lines L are printed on the sheet 12, the ink ribbon 14 adheres to the sheet at the lateral line L, but does not adhere to the sheet in the spaces between the lines L. Consequently, as shown in FIG. 3A, the ink ribbon 14 may remain adhered to the sheet 12 after passing the curve 16a, and may abruptly separate from the sheet 12 (as shown in FIG. 3B). This type of abrupt separation of the ink ribbon 14 generates vibration and noise. Accordingly, if such a conventional thermal transfer printing mechanism is employed in a facsimile device, the generated noise during operation can become unacceptable.